1. Technical Field
The present invention is directed generally to modules, and, in particular, to pneumatic modules.
2. Description of the Related Art
It is known to provide a pneumatic module configured to selectively control the flow of fluid from a first port to a second port, as seen by reference to U.S. Pat. No. 6,409,145 to Fong et al (“Fong”). Fong discloses an armature in combination with a valve seat to implement this fluid control. However, a problem generally encountered in the pneumatic module field involves providing a device to simultaneously meet the requirements of low internal leakage in both fluid flow directions, high operating pressure, low noise, low cost and ease of assembly. Pneumatic modules having low internal leakage in only one flow direction are inefficient in systems requiring effective sealing to prevent fluid backflow. Such internal leakage is often caused by the failure of the armature to make effective contact with the valve seat or when pressure forces act to unseal the armature. However, even those pneumatic modules having low internal leakage in both directions are often limited to use only in low pressure applications. The inability for such actuators to withstand higher pressures makes these actuators undesirable for high pressure environments. It is also desirable to reduce the mechanical noise generated when the armature contacts the valve seat. Finally, to make pneumatic modules more cost effective, they should be designed to eliminate steps in the assembly process and/or to eliminate unnecessary internal components.
Accordingly, there is a need for a pneumatic module that minimizes or eliminates one or more of the above-mentioned shortcomings.